<?php

namespace DaftPlug\Rankify\Features\Meta;

use DaftPlug\Rankify\Helpers\Utils;

if (!defined('ABSPATH')) {
  exit();
}

/**
 * Open Graph and X (Twitter) card tags.
 *
 * X card values fall back to the Open Graph ones rather than being emitted
 * twice: X reads og:* when the twitter:* equivalent is absent, so duplicating
 * them only adds bytes. Only the two tags with no Open Graph equivalent —
 * twitter:card and the account handles — are always printed.
 */
class Social
{
  /**
   * Other plugins that emit the same tags. Detected so the admin can warn
   * about it; two sets of og:title in one document is a real problem, and the
   * scrapers pick unpredictably between them.
   */
  const CONFLICTING_PLUGINS = [
    'wordpress-seo/wp-seo.php' => 'Yoast SEO',
    'seo-by-rank-math/rank-math.php' => 'Rank Math',
    'all-in-one-seo-pack/all_in_one_seo_pack.php' => 'All in One SEO',
    'wp-seopress/seopress.php' => 'SEOPress',
    'autodescription/autodescription.php' => 'The SEO Framework',
    'slim-seo/slim-seo.php' => 'Slim SEO',
  ];

  public function __construct()
  {
    add_action('wp_head', [$this, 'output'], 2);
  }

  /**
   * Active plugins that also emit social/meta tags.
   *
   * @return array<string,string> plugin file => display name
   */
  public static function detectConflicts()
  {
    if (!function_exists('is_plugin_active')) {
      $lib = path_join(ABSPATH, 'wp-admin/includes/plugin.php');
      if (!file_exists($lib)) {
        return [];
      }
      include_once $lib;
    }

    $found = [];
    foreach (self::CONFLICTING_PLUGINS as $file => $name) {
      if (is_plugin_active($file)) {
        $found[$file] = $name;
      }
    }

    return $found;
  }

  public function output()
  {
    $context = Context::current();

    if (!$this->shouldOutput($context)) {
      return;
    }

    if ('on' === Utils::getSetting('openGraph')) {
      $this->printOpenGraph($context);
    }

    if ('on' === Utils::getSetting('twitterCards')) {
      $this->printTwitterCard($context);
    }
  }

  protected function printOpenGraph(Context $context)
  {
    $title = $this->socialValue($context, 'og_title', Resolver::title($context));
    $description = $this->socialValue($context, 'og_description', Resolver::description($context));
    $url = Resolver::canonical($context) ?: Utils::getCurrentUrl(true);

    $this->tag('og:locale', get_locale());
    $this->tag('og:site_name', get_bloginfo('name'));
    $this->tag('og:type', $this->openGraphType($context));
    $this->tag('og:title', $title);
    $this->tag('og:description', $description);
    $this->tag('og:url', $url);

    $image = Resolver::image($context);
    if ('' !== $image['url']) {
      $this->tag('og:image', $image['url']);
      // Dimensions let a scraper lay the card out before it has fetched the
      // file, which is the difference between a card rendering immediately and
      // rendering blank on first share.
      if ($image['width'] && $image['height']) {
        $this->tag('og:image:width', (string) $image['width']);
        $this->tag('og:image:height', (string) $image['height']);
      }
      if ('' !== $image['type']) {
        $this->tag('og:image:type', $image['type']);
      }
      if ('' !== $image['alt']) {
        $this->tag('og:image:alt', $image['alt']);
      }
    }

    if (Context::TYPE_SINGULAR === $context->type && $context->hasPost()) {
      $this->printArticleTags($context);
    }
  }

  protected function printArticleTags(Context $context)
  {
    $post = $context->object;

    $this->tag('article:published_time', get_post_time('c', true, $post));
    $this->tag('article:modified_time', get_post_modified_time('c', true, $post));

    $author = get_the_author_meta('display_name', (int) $post->post_author);
    if ($author) {
      $this->tag('article:author', $author);
    }

    $terms = get_the_terms($post, 'category');
    if (!empty($terms) && !is_wp_error($terms)) {
      $this->tag('article:section', $terms[0]->name);
    }

    $tags = get_the_terms($post, 'post_tag');
    if (!empty($tags) && !is_wp_error($tags)) {
      foreach ($tags as $tag) {
        $this->tag('article:tag', $tag->name);
      }
    }
  }

  protected function printTwitterCard(Context $context)
  {
    $image = Resolver::image($context);

    // summary_large_image needs an image to be large about. Without one X
    // renders the small card regardless, so declaring it would be a lie.
    $card = '' !== $image['url'] ? 'summary_large_image' : 'summary';
    $this->nameTag('twitter:card', $card);

    $site = Utils::getSetting('socialTwitterSite');
    if (is_string($site) && '' !== trim($site)) {
      $this->nameTag('twitter:site', $this->handle($site));
    }

    // Only emitted when it differs from the Open Graph value; X falls back to
    // og:title and og:description on its own.
    $title = $this->socialValue($context, 'twitter_title', '');
    if ('' !== $title) {
      $this->nameTag('twitter:title', $title);
    }

    $description = $this->socialValue($context, 'twitter_description', '');
    if ('' !== $description) {
      $this->nameTag('twitter:description', $description);
    }

    $twitterImage = Resolver::override($context, 'twitter_image');
    if ('' !== $twitterImage) {
      $this->nameTag('twitter:image', $twitterImage);
    }
  }

  /**
   * Open Graph type for this view. Only 'article' and 'website' are used —
   * the richer types require properties we do not collect, and an incomplete
   * og:type is treated as invalid rather than ignored.
   */
  protected function openGraphType(Context $context)
  {
    if (Context::TYPE_SINGULAR === $context->type && $context->hasPost() && 'page' !== $context->postType) {
      return 'article';
    }

    if (Context::TYPE_AUTHOR === $context->type) {
      return 'profile';
    }

    return 'website';
  }

  /**
   * A social-specific override, falling back to the shared value.
   */
  protected function socialValue(Context $context, $field, $fallback)
  {
    $override = Resolver::override($context, $field);
    if ('' !== $override) {
      return Variables::resolve($override, $context);
    }

    return $fallback;
  }

  protected function handle($value)
  {
    $value = trim($value);

    // Accept a full profile URL, an @handle or a bare handle. The pattern is
    // delimited with #, so the fragment marker inside the class is escaped.
    // An unescaped # ends the pattern early and PHP warns "Unknown modifier ']'".
    if (preg_match('#(?:twitter|x)\.com/([^/?\#]+)#i', $value, $matches)) {
      $value = $matches[1];
    }

    return '@' . ltrim($value, '@');
  }

  protected function tag($property, $content)
  {
    if ('' === (string) $content) {
      return;
    }

    printf('<meta property="%1$s" content="%2$s" />' . "\n", esc_attr($property), esc_attr($content));
  }

  /**
   * X reads name= rather than property=. Both work in practice, but the
   * documented form is name= and validators flag the other.
   */
  protected function nameTag($name, $content)
  {
    if ('' === (string) $content) {
      return;
    }

    printf('<meta name="%1$s" content="%2$s" />' . "\n", esc_attr($name), esc_attr($content));
  }

  protected function shouldOutput(Context $context)
  {
    if (is_feed() || is_admin() || is_embed()) {
      return false;
    }

    if (defined('REST_REQUEST') && REST_REQUEST) {
      return false;
    }

    // A noindexed page has no business generating a share card either.
    $robots = Resolver::robots($context);
    if (isset($robots['index']) && 'noindex' === $robots['index']) {
      return false;
    }

    return (bool) apply_filters('rankify_output_social_tags', true);
  }
}